Fluid rotary actuator



Aug. 23, 1966 R. R. ADAMS FLUID ROTARY ACTUATOR Filed Aug. s, 1962 28 I6 4f: l|| l INVENTOR.

RUDOLPH R. ADAMS M ,El mw ATTORNEY United States Patent O 3,267,817 FLUID RUTARY ACTUATOR Rudolph R. Adams, Cleveland, Ohio, assignor to Graham Engineering Company, Inc., Palo Alto, Calif., a corporation of California Filed Aug. 8, 1962, Ser. No. 215,665

4 Claims. (Cl. 91-186) The present invention relates generally to fluid devices :and more particularly to that class of fluid devices which are known as fluid actuators and which convert fluid pressure to rotary motion.

lin the rotary type ot dluid :actuators rectilinear mo- 4rtion of ya piston causes an output shaft to rotate. AIn

the past this change from a rectilinear to a rotary motion has been accomplished in several ways. Some prior rotary devices use a connecting rod and crank arrangement. Other prior rotary devices use a rack and gear arrangement, while still others rely on a lever arrangement.

All of these prior devices are lacking in that (1) they require complex mechanisms external of the piston cylinder, (2) they have high frictional losses, and (.3) they require excessive space. The entire device required t-o convert reciprocating t-o rotary motion has required a great ydeal of space and orten has been awkward to mount in the position necessary for i-ts use, especially in tight or condined locations. The degree of rotation of these prior devices are generally limited to a xed value or values, with no provision for adjustment. In those few devices where mechanisms for changing the degree of rotation are provided, such mechanisms are quite complex involving added material and expense. Finally, many of the prior devices are not desirable because they provide a varying torque output :as a result of rthe very nature of their mechanical movement.

In the preferred form of the fluid device of the invention a cylinder block is provided with two piston cylinders and two pistons slidable in the piston cylinders. A shaft is rotatably journaled in the cylinder block. The two pistous are operatively connected to the rotatable shaft by a dlexible member reeved over a pulley. The pulley is lixed to the shaft and rotates therewith while the llexible member interconnects the pistons. When one piston is in its retracted position near the pulley, the other piston is in an extended position remote from the pulley. The cylinders each include a port for pressurizing and exhausting the cylinders on the face side of the pistons. A third port is provided in the cylinder block to apply a constant pressure between the pistons which equals the pressures applied to the cylinder ports. To obtain rotation of the shaft when the huiddevlice ofthe invention li-s used as an actuator the cylinders are alternately pressurized and exhausted.

Accordingly, an object of the present invention is to provide a new and improved device for converting fluid pressure to rotary mechanical motion.

Another object of the present invention is to provide a new and improved fluid device for converting uid pressure into a rotary mechanical motion of a const-ant torque.

A further object of the present invention is to provide la new and improved plural piston device for providing rotary mechanical motion from a fluid pressure wherein at least two pistons are operatively connected to a rotating drive wheel by a flexible drive and simultaneous re ciprocal motion of the pistons is caused by applying equal pressure t-o the backs of the pistons and to the face of at least one piston and by exhausting the face of at least one other piston.

3,267,817 Patented August 23, 1966 lCC Still another object of the present invention is to provide a new and improved rotary device having a piston operatively connected to a drive wheel wherein the degree of rotation of the wheel may be selectively set by adjusting the length of the piston travel.

Yet another object of the present invention is to provide a new and improved rotary device having a reciprocating piston operatively connected to a drive wheel by a flexible drive wherein the eXible adrive is maintained in a tensed state when the rotary device is in use.

A final object of the present invention is to provide a new and improved device for converting between iluid pressure and a rotary mechanical motion wherein such device is extremely simple in construction and operation and has a minimum of moving parts.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which:

FIGURIE 1 is a ront cross-sectional view ot the rotary actuator of the invention;

FIGURE 2 is a side, cross-sectional view of the rotary actuator of FIGURd-l 1; and,

`FIGURE 3 is -a front elevational view, partially in section, showing an valternate form ofthe rot-ary uid actuator of the invention.

Referring now to the drawing a fluid rotary device is indicated generally by the reference character 11 in FIG- URE 1. The fluid device 1v1 includes a cylinder block, or housing, 12. The cylinder block 12 includes a drive wheel compartment 13 and is bored between the drive wheel compartment and one end to provide two parallel piston cylinders 14 and 1.5'. A journal bearing 16 and an end bearing 17 are provided on either side of the drive Wheel compartment 16. Machine screws are normally provided to secure the bearings 16, 17 to the cylinder block 12. The bearings 1'6, 17 include a collar portion 118, 19, respectively. The collar portions 18, 19 are received in collar bores 21, 22 in the cylinder block 12 on both sides of the drive wheel compartment. Sealing rings 213, 24 are provided around the collar portions 18, 19. Each bearing 1'6, 17 includes a bronze bushing 26, 27, respectively.

A drive shaft 2-8 is rotatably journaled in the bushings 26, 27. A drive sprocket wheel 29 is fixed to the drive shaft and positioned in the drive Wheel compartment 13. The sprocket is sized such that its pitch diameter is the distance between the centers of the parallel piston bores 14, 15. The inside ends of the bronze bushings 26, 27 maintain the sprocket wheel 29 in the `center ot the drive wheel compartment 1-3. A sealing ring 31 is provided around the drive shaft 28 within the journal bearing 16.

T'w-o pistons 32, 33 are provided which are respectively disposed in the cylinders 14, 15. Packings 34, 35 are provided around the pistons 32, 33, respectively. A link chain 36 interconnects the pistons 312, 33 and is reeved over the sprocket Wheel 29. The links of the chain 36 operatively engage teeth on the sprocket wheel t-o provide a positive drive connect-ion between the pistons 32, 33 and the drive shaft 28. The link chain 36 is sized to position one piston in a retracted position adjacent the drive wheel compartment when the other piston is moved to an extended position away from the drive wheel compartment 13.

A cover -plate 42 is secured to the end of the cylinder block 12 to enclose the drive wheel compartment 13. A sealing ring 43 is provided between the cover plate 42 and the cylinder block 12. A pair of piston stops 44, 45

are provided to limit the travel of the pistons 32, 33 towards the retracted position adjacent the drive wheel cornpartment 13. Adjustment screws 46, 4-7 are pro'vided to set the vertical position of the piston stops 44, 45. The adjustment screws 46, 47 turn freely in the cover plate 42 to move .their respective piston stops 44, 45 laxiially Iin the piston cylinders 14, 15.

A cylin-der head plate 49 is removably secured to the cylinder block 12 to enclose the piston cylinders 14, 15. Sealing rings 50, 51 are provided between the cylinder block 12 vand the cylinder lhelad plate 49.

Fluid ports 52, 53 are provided in the cylinder head plate 49 to pressurize and exhaust ythe piston cylinders 14, 15. Fluid hoses 54, S5 are connected to the uid ports 52, 53, respectively. A fluid port 56 is also provided in the cylinder head plate 49. The fluid port 56 is connected to the drive wheel compartment 13 by a fluid passageway 57 formed in the wall dividing the piston cylinders 14, 15. A sealing ring 59 is provided around the Huid port 56 between the cylinder head plate 49 and the cylinder block 12. A fluid hose 58 is connected to the liuid port 56. A constant pressure P is normally introduced into the drive wheel compartment 13 through the fluid port 56. This pressure pushes against the back of the pistons 32, 33 to tense the connecting link chain 36. Maintaining the pressure P throughout the operation of the fluid device 11 prevents kinking of the link chain 36, thus permitting the fluid `device 11 to operate smoothly.

When the iiuid device 11 is in use the shaft 28 is caused to rotate in Van oscillator manner by alternately pressurizing and exhausting the ports S2, 53. First, a constant pressure P is applied to the port 56. Then, to obtain clockwise rotation of the shaft 28 a pressure P1, equal to P, is applied to the port 52. When the port 53 is exhausted El, the pistons 32, 33 are caused to move to their solid line positions shown. To obtain counterclockwise rotation of the shaft 28 a pressure P2, equal to the pressure P1 is applied to the port 53. When the port 52 is exhausted E2 the pistons 32, 33 are caused to move to the phantom position 32', 33'.

The exact degree of rotation of the shaft 28 is adjusted by turning the piston fstop adjustment screws 46, 47 to regulate the travel of the pistons 32, 33 in the pist-on cylinders 14, 15. The total available degree of rotation of the shaft 28 is determined by the pitch diameter of the sprocket wheel 29 and the available length of piston travel.

The torque applied to or received from the shaft 28 is determined by the pressure applied at the ports 52, 53 and 56, the size of the pistons 32, 33 and the pitch diameter yof the `sprocket wheel 29. When the fluid device 11 is in use adjustments in the torque yat shaft 28 are easily obtained by regulating the pressure applied to the ports 52, 53 and 56.

FIGURE 3 illustrates an alternate form of the fluid device 11 wherein a constant pressure P, equal to the pressures P1, P2, is admitted to the drive wheel compartment 13 without the need for the fluid port 56 and the fluid passageway 5'7. Pistons 62, 63 of the fluid actuator 11 are provided with check valves 64, 65. When pressure is applied to the port 52 the ball 66 of the check valve 64 is moved against the spring 67 to permit the fluid to pass into the drive wheel compartment 13. The ball 66 remains in this open position until the pressure in the drive whee-l compartment 13 is equal to the pressure applied to the face of the piston 62. Exhausting the port '53 induces rotation of the shaft 28. When the procedure is reversed and fluid pressure is applied to port 53 the check valve 65 of piston 63 admits the fluid, if required, to the ldrive wheel compartment 13 to assure that a pressure P is maintained the-rein.

Although the specification describes the fluid device of the invention in detail, it is believed to comprise essentially acylinder block having a plurality of piston bores,

pistons slidably disposed in the bores and interconnected by a flexible drive, which drive operatively engages a drive wheel disposed in a ydrive wheel compartment of the cylinder block, the cylinder block including ports to pressurize and exhaust the piston bores, and means to apply pressure to the interconnected sides of the pistons to maintain the flexible drive in a tensed condition.

Although the linvention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. A uid device comprising:

(a) a cylinder block having first and second piston bores therein and a drive wheel compartment communicating with each of said iirst and second piston bores;

(b) first and second pistons disposed in -said first and second bores, respectively, both said pistons being slidable in their respective bores betweenia retracted position near said drive wheel compartment and an extended position distant from said drive wheel compartment;

(c) said cylinder block having first and second ports opening into said first and sec-ond piston bores, respectively, to pressurize 'and exhaust said piston bores;

(d) drive wheel means rotatably supported within said `drive wheel compartment;

(e) a bendable drive means interconnecting the pistons and operatively engaging the drive wheel means to inter-transmit mechanical power between said drive wheel and said pistons, and

(f) said first and second pistons each including a check valve therein, said check valves each passing fluid through the piston into the drive wheel compartment only.

2. The fluid device of claim 1 including in combination:

(a) piston stop means engaging said pistons in the retracted position, and said piston stop means being adjustably movable in said piston bores to limit the movement of said pistons toward the retracted position.

3. A rotary fluid device comprising:

(a) a cylinder block having first and second piston bores and a sprocket compartment communicating with both said first and second piston bores;

(b) a shaft passing through said sprocket compartment and rotatably journaled in said cylinder block;

(c) a sprocket fixed to sai-d shaft within said sprocket housing;

(d) first and second pistons slidably disposed in said first land second piston bores, respectively, said pistons being slid-able in their bores between a retracted position near said sprocket and an extended position distant from said sprocket;

(e) a chain interconnecting said first and second pistons and passing over said sprocket so as to operatively engage the teeth thereof;

(f) said chain being sized to bring one of said pistons to the retracted position when the other of said pistons is moved to the extended position;

(g) first and second fluid ports -opening into said first and second piston bores, respectively, to pressurize and exhaust said piston bores; and

(h) said pistons each including a check valve therein,

each such check valve passing fluid through its respective piston into said ysprocket compartment only, thereby maintaining said chain in a tensed condition when the rotary device is in use..

4. The rotary Huid device of claim 3, including, in combination:

(1) piston stop means engaging said pistons in the re tracted position, and said piston stop means being adjustably movable in said piston bores to limit the movement of said pistons toward the retracted position.

UNITED References Cited by the Examiner STATES PATENTS McGowan 9213 Fournia 92--13 Demand 121-117.1

Vaughan 91-186 Kuskin 121-117.1

Fuller 91-172 6 11/ 1945 Van Der Weric 91--422 9/ 1957 Black 91-422 11/1960 Elliott 121-177.1 3/1961 Liggett et a1 91-186 3/1963 Fowler et al 92-13 FOREIGN PATENTS 2/ 1877 Great Britain. 12/ 1908 Great Britain.

9/ 1953 Italy.

EDGAR W. GEOGHEGAN, Primary Examiner.

RICHARD B. WILKINSON, FRED E. ENGEL- THALER, Examiners.

15 i. LABOWSKY, P. E. MASLOUSKY,

Assistant Examiners. 

1. A FLUID DEVICE COMPRISING: (A) A CYLINDER BLOCK HAVING FIRST AND SECOND PISTON BORES THEREIN AND A DRIVE WHEEL COMPARTMENT COMMUNICATING WITH EACH OF SAID FIRST AND SECOND PISTON BORES; (B) FIRST AND SECOND PISTONS DISPOSED IN SAID FIRST AND SECOND BORES, RESPECTIVELY, BOTH SAID PISTONS BEING SLIDABLE IN THEIR RESPECTIVE BORES BETWEEN A RETRACTED POSITION NEAR SAID DRIVE WHEEL COMPARTMENT AND AN EXTENDED POSITION DISTANT FROM SAID DRIVE WHEEL COMPARTMENT; (C) SAID CYLINDER BLOCK HAVING FIRST AND SECOND PORTS OPENING INTO SAID FIRST AND SECOND PISTON BORES, RESPECTIVELY, TO PRESSURIZE AND EXHAUST SAID PISTON BORES; (D) DRIVE WHEEL MEANS ROTATABLY SUPPORTED WITHIN SAID DRIVE WHEEL COMPARTMENT; (E) A BENDABLE DRIVE MEANS INTERCONNECTING THE PISTONS AND OPERATIVELY ENGAGING THE DRIVE WHEEL MEANS TO INTER-TRANSMIT MECHANICAL POWER BETWEEN SAID DRIVE WHEEL AND SAID PISTONS, AND (F) SAID FIRST AND SECOND PISTONS EACH INCLUDING A CHECK VALVE THEREIN, SAID CHECK VALVES EACH PASSING FLUID 